The 19-year-old Famous in Love star gushed about the 27-year-old Café Society actress while discussing her desire to date a woman in an interview with Harper's Bazaar.
"She's so hot," she said of Stewart. "She seems like the raddest chick, I'd be so down."
Thorne, who has dated Gregg Sulkin and Tyler Posey, came out as bisexual on Twitter in August. She admitted in the interview that she has a hard time reading and is often "confused" by signals from women.
"I've done other stuff with girls, but I really want to actually date a girl," the star told the magazine.
"I can't tell if a girl is hitting on me or she just wants to be friends," she explained. "And I don't want to flirt with a girl if she thinks I'm just being her friend. What if I kiss a girl and she's like, 'Oh, I'm just your friend dude, I can't believe you crossed that boundary.'"
Thorne named fellow former Disney stars Demi Lovato and Miley Cyrus as her celebrity crushes in an interview with Maxim in October. She said at the time that she faced backlash after coming out as bisexual.
"I have already had people talk [expletive] to me," the actress said. "And it comes from people in the industry, not even fans. I've had studios tell me my image is too 'out there,' hinting at it but not really saying it."
Thorne plays Paige Townsen on Famous in Love, which will premiere April 18 on Freeform. Stewart, who said in the November issue of Elle that she's "not ashamed" of her fluid sexuality, will next star in Lizzie with Chloe Sevigny.